Crawler drive mechanism



W. G. VAN VOORHIS CRAWLER DRIVE MECHANISM May 25, 19 43.

Filed Sept.. 19, 1941 INYENTOR ATTORNEY Patented May 25, 1943 CRAWLER DRIVE MECHANISM William G. Van Voorhis, Findlay, Ohio, assignor to The Buckeye Traction Ditcher Company, Findlay, Ohio, a corporation of Ohio Application September 19, 1941, Serial No. 411,508

2 Claims. (Cl. 305-4)):

This invention relates to crawler driven machines of the type having a pair of laterally spaced crawler units providing the tractive power for the machine, but more particularly to machines of this character in which the crawler units are operated by a sprocket and chain drive.

Heretoiore the tension on the drive chains would, from time to time, require adjustment because, in the case of improper chain adjustment, a tendency for the chain to climb the sprocket, would be created and in such event costly damage to the driving as well as driven parts would occur. Ordinarily, to correct this difficulty and to effect proper tensioning of the driving chains, certain of the parts would be shimmed. This has proved to be very costly and difiicult because of the necessity of tearing down certain parts of the machine and the time consumed in accomplishing the work.

An object is to produce a simple and efiicient means by which the tension of the crawler driving chains can be adjusted conveniently and Without putting the machine out of use for any substantial period of time.

Another object is to produce new and improved crawler drive mechanism involving sprocket and chain drive for the crawler units by which the tension on the chain drive can be readily and conveniently adjusted.

Other objects and advantages of the invention will hereinafter appear and for purposes of illustration but not of limitation, an embodiment of the invention is shown on the accompanying drawing in which Figure 1 is a fragmentary side elevation of a crawler driven tractor, only so much of the machine being shown as to illustrate the embodiment of the invention;

Figure 2 is a top plan view of a portion of the main frame of the tractor showing the adjustably mounted crawler drive assembly; and

Figure 3 is an enlarged end elevation of the crawler drive assembly showing particularly the pivotal mounting thereof and the adjusting means therefor.

The illustrated embodiment of the invention comprises a tractor T having a main supporting frame In supported by a pair of laterally spaced crawler units I I, only one of which is shown although it will be understood that a similar arrangement is disposed on the opposite side of the machine. Crawler drives are old and well-known in the art and detail description and illustration thereof is, therefore, not considered necessary since the particular structure and mounting of advantageously employed in connection with any crawler driven tractor.

The endless belt H of each crawler unit H is trained about a driving wheel I 3 which rotates with a driven sprocket M. The sprocket I4 is connected by an endless chain I5 to a smaller driving sprocket [6. The drivingsprockets l6 are secured to shafts I! and Ila respectively and these shafts form a part of a right angle drive unit indicated at I8. As shown on the drawing, the drive unit comprises a housing having a pair of relatively large parts l9 and a relatively small connecting part 20. Power is delivered to the drive unit l8 from a pair of drive shafts 2| having universal joint connections 22 respectively with the parts contained within the housing parts l9, one drive shaft being provided for each of the crawler units l I. The drive shafts 2| extend rearwardly and downwardly from the drive unit and receive their power from a power plant 23. The operative connections from the power plant 23 to the drive shafts 2| are generally indicated on Fig. 1 of the drawing but since these particular connections form no part of the present invention and will be readily understood by those skilled in the art, detail description and illustration thereof are not considered necessary.

It will be observed that the main frame Ill includes longitudinally extending beams 24 and a transverse connecting beam 25 in the forward end of the longitudinally disposed beams. The right angle drive unit I8 is pivotally connected for swinging movements about a horizontal axis with respect to the transverse beam 25. It will be observed that each of the housing parts l9 has an outwardly extending flange terminating in a bracket 26 disposed slightly rearwardly of the top center portion of the respective housing and fixed to the upper side of the transverse beam 25 is a pair of laterally spaced brackets 21. Each bracket 21 has a forked end 28 which straddles one of the housing brackets 26. A pin 29 passes through the forked end 28 and the respective housing bracket 26 thereby pivotally to support opposite end portions of the drive unit 18.

On the under side of each of the housing portions [8 is a depending bracket 30 which is disposed slightly rearwardly of the lower central portion of the respective housing portion directly beneath the bracket 26. Pivotally connected by a pin 3| to each of the brackets 30 is a screwthreaded rod 32 which passes through an opening in a forwardly inclined bracket 33 fixed to and depending from the under side of the transverse beam 25. Nuts 34 engage the threaded portion of the rod 32 on opposite sides of the bracket 33 and securely hold the parts in adjusted position.

It will be apparent that the tension on the endless chains [5 can be readily adjusted by loosening the nuts 34 and swinging the drive unit is about its pivot pins 29 to take up slack in the chains I5 or relieve the tension thereon according to the direction of adjusting movement. Thereafter by tightening up on the nuts 35, the parts will be securely held in the adjusted position.

From the above description, it will be manifest that an extremely simple' but thoroughly satisfactory means for adjusting the tension on the endless chains [5 is provided, enabling the tension on these chains to be adjusted in an extremely short period of time. This is obviously a decided improvement over previous methods employed by which shims were employed. to increase or diminish the tension imposed on the driving chains.

It is to be understood that numerous changes in details of construction, arrangement and operation may be effected without departing from the spirit of the invention especially as defined in the appended claims.

a l mi r H 1. The combination of a horizontally disposed main frame, a pair of laterally spaced crawler units providing traction for said frame, a drive mechanism for said crawler units including a power operated drive shaft, a transversely arranged unitary assembly, a universal joint providing a driving connection between said drive shaft and assembly, said assembly having a driving sprocket for each crawler unit, a driven sprocket operatively connected toeach crawler unit, a chain connecting each pair of driving and driven sprockets, a hinge connection between the upper portion of said assembly and main frame enabling rocking movement of said assembly relative to the main frame about a horizontally disposed axis; and means at the lower portion of said assembly providing a connection between same and said main frame for effecting the desired rocking of the assembly for regulating the chain tension;

2. The combination of a horizontally disposed main frame, a pair of laterally spaced crawler units providing traction for said frame, a drive mechanism for said crawler units including a power operated drive shaft, a transversely arranged unitary assembly, a universal joint providing a driving connection between said drive shaft and assembly, said assembly having a driving sprocket for each crawler unit, a driven sprocket operatively connected to each crawler unit, a chain connecting each pair of driving and driven sprockets, a hinge connection between one portion of said assembly and main frame enabling rocking movement of said assembly relative to the main frame about a horizontally disposed axis, and meansadjacent another portion of said assembly providing a connection between same and said main frame for effecting the desired rocking of the assembly for regulating the chain tension.

WILLIAM G. VAN VOORHIS. 

